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<DIV CLASS="navbar"><A HREF="http://vt100.net/"><IMG CLASS="button" SRC="vt100.net-logo.png" ALT="VT100.net" HEIGHT="16" WIDTH="102"></A> VT330/VT340 Programmer Reference Manual Volume 2: Graphics Programming<TABLE WIDTH="100%">
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<TD ALIGN="LEFT"><A HREF="../../index.html">Appendix B</A></TD>
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<H1 ID="SG">Glossary</H1>
<DL>
<DT ID="TWOPLANE">2-plane bitmap</DT>
<DD><P>Graphics page memory for the VT330. In a 2-plane bitmap, each <A HREF="#PIXEL">pixel</A> is represented
by a 2-bit code. A 2-bit code has four possible values, so the VT330 can
display up to four different shades of gray at a time.</P></DD>
<DT ID="FOURPLANE">4-plane bitmap</DT>
<DD><P>Graphics page memory for the VT340. In a 4-plane bitmap, each <A HREF="#PIXEL">pixel</A> is represented
by a 4-bit code. A 4-bit code has 16 possible values, so the VT340 can
display up to 16 different colors or shades at a time.</P></DD>
<DT ID="ABSOLUTE">Absolute location</DT>
<DD><P>An unsigned coordinate pair that specifies a location based on the screen origin.
For example, [X,Y].</P></DD>
<DT ID="ACTIVE">Active position</DT>
<DD><P>The current cursor location. Usually, the point that was last moved to or drawn
to.</P></DD>
<DT ID="BACKGROUND">Background intensity</DT>
<DD><P>The color or shade of the background on the screen.</P></DD>
<DT ID="BOUNDED">Bounded position stack</DT>
<DD><P>An option to the ReGIS vector or position command that lets you save the last
active position by pushing it onto a stack. You can return the active position to
the last saved position by popping the saved position off the stack.</P></DD>
<DT ID="CLOSED">Closed curve sequence</DT>
<DD><P>A series of locations the terminal uses to interpolate a curve whose endpoints
meet.</P></DD>
<DT ID="COLOR">Color map</DT>
<DD><P>In the VT330, the four output map locations used to store a monochrome intensity
value.</P>
<P>In the VT340, the 16 output map locations used to store intensity values. Each
location has a monochrome and a color intensity value.</P></DD>
<DT ID="COMMAND">Command key letter</DT>
<DD><P>A single letter that identifies the beginning of a ReGIS command. For example,
P identifies a position command.</P></DD>
<DT ID="COMPLEMENT">Complement writing</DT>
<DD><P>A ReGIS writing style that lets you draw over an image, using the "opposite"
shade or color. Complement writing ignores the current <A HREF="#FOREGROUND">foreground intensity</A>,
and affects only those areas defined by 1 bits (foreground) in the bit pattern
memory.</P></DD>
<DT ID="COORDINATE">Coordinate pair</DT>
<DD><P>Two values [X,Y] that define a specific location on the screen. The X value
defines a location parallel to the horizontal axis. The Y value defines a location
parallel to the vertical axis.</P></DD>
<DT ID="CURVE">Curve interpolation</DT>
<DD><P>The action the terminal takes to complete a curve, based on a series of coordinates
you specify.</P></DD>
<DT ID="DEFAULT">Default</DT>
<DD><P>A standard value used by the terminal when the user or program does not
specify a value.</P></DD>
<DT ID="DISPLAYADDRESSING">Display addressing</DT>
<DD><P>The limits of the screen area used for drawing graphics. The terminal uses
screen coordinates to address (draw or move to) a point on the screen. The
default limits for the VT300 are the coordinates [0,0] and [799,479].</P></DD>
<DT ID="DISPLAYCELL">Display cell</DT>
<DD><P>The size of the screen area used to display each character. The same display
cell is used for all characters.</P></DD>
<DT ID="ERASE">Erase writing</DT>
<DD><P>A ReGIS writing style that lets you write over an existing image by using the
background color.</P></DD>
<DT ID="FOREGROUND">Foreground intensity</DT>
<DD><P>The color or shade of the foreground on the screen. The terminal uses this
color/shade to draw images when you use the overlay or replace writing style in
ReGIS.</P></DD>
<DT ID="GRAPHICS">Graphics cursor</DT>
<DD><P>An indicator that represents the active position on the screen when you use
ReGIS. There are two types of graphics cursor, an <A HREF="#INPUT">input cursor</A> and an <A HREF="#OUTPUT">output
cursor</A>. You can use the default cursor characters or select your own.</P></DD>
<DT ID="GRAY">Gray scale</DT>
<DD><P>In the VT330, the four levels of intensity used for drawing, ranging from white
to black.</P>
<P>In the VT340, the 16 levels of intensity used for drawing, ranging from white
to black.</P></DD>
<DT ID="HLS">HLS color system</DT>
<DD><P>A color coordinate system for specifying colors, based on their hue, lightness,
and saturation. See <A HREF="#RGB">RGB color system</A>.</P></DD>
<DT ID="INPUT">Input cursor</DT>
<DD><P>A <A HREF="#GRAPHICS">graphics cursor</A> that appears when the terminal is in ReGIS graphics input
mode. The default input cursor is a crosshair.</P></DD>
<DT ID="LINE">Line pattern</DT>
<DD><P>An 8-bit pattern that ReGIS uses to draw lines. You can use a standard pattern
or select your own.</P></DD>
<DT ID="MACROGRAPH">Macrograph</DT>
<DD><P>A stored string of ReGIS commands or command segments. You use a single
letter to name each macrograph. You use macrographs to store text and commands
that you use repeatedly.</P></DD>
<DT ID="MASK">Mask specifier</DT>
<DD><P>One or more characters you can use to define a new graphics cursor style. The
mask specifier can be a loaded, or built-in character.</P></DD>
<DT ID="MNEMONIC">Mnemonic</DT>
<DD><P>An abbreviation or acronym for a command or a control character.</P></DD>
<DT ID="MONOCHROME">Monochrome map</DT>
<DD><P>The four output map locations that the VT330 uses to select the intensity of
the display. Each location stores a different intensity, from white to black.</P></DD>
<DT ID="OFFSET">Offset</DT>
<DD><P>A distance from a given location.</P></DD>
<DT ID="OPEN">Open curve sequence</DT>
<DD><P>A series of points that the terminal uses to interpolate a curve whose endpoints
do not necessarily meet.</P></DD>
<DT ID="OUTPUT">Output cursor</DT>
<DD><P>A <A HREF="#GRAPHICS">graphics cursor</A> that appears when the terminal is waiting for ReGIS input
from the host system. The output cursor indicates the current drawing position.
The default output cursor is a diamond.</P></DD>
<DT ID="OVERLAY">Overlay writing</DT>
<DD><P>A ReGIS writing style that lets you draw only in the foreground, not the
background.</P></DD>
<DT ID="PIXEL">Pixel</DT>
<DD><P>A picture element. The smallest displayable unit on the screen.</P></DD>
<DT ID="PIXELVECTOR">Pixel vector (PV) system</DT>
<DD><P>In ReGIS, a method for selecting the direction to draw or move incrementally
on the screen. You can select from eight different directions, at 45 degree increments.</P></DD>
<DT ID="POSITION">Position stack</DT>
<DD><P>A set of coordinate positions that ReGIS uses in sequence. You use position
stacks to move the cursor to several positions in a single vector or position
command. There are two types of position stacks, <A HREF="#BOUNDED">bounded</A> and <A HREF="#UNBOUNDED">unbounded</A>.</P></DD>
<DT ID="PVMULTIPLICATION">PV multiplication factor</DT>
<DD><P>An integer used to select the number of pixels to move for each PV value
specified. ReGIS uses the PV multiplication factor for all PV values you enter.
You can change the PV multiplication factor.</P></DD>
<DT ID="RELATIVE">Relative location</DT>
<DD><P>A point on the screen measured from a specified location, rather than from the
<A HREF="#SCREEN">screen origin</A>.</P></DD>
<DT ID="REGIS">ReGIS</DT>
<DD><P>Digital's graphics instruction set that lets you build images from standard geometric
forms, such as lines, curves, and circles.</P></DD>
<DT ID="REPLACE">Replace writing</DT>
<DD><P>A ReGIS writing style that lets you draw in both the foreground and the
background.</P></DD>
<DT ID="RGB">RGB color system</DT>
<DD><P>A coordinate system for specifying colors, based on the three primary colors
red, green, and blue. See <A HREF="#HLS">HLS color system</A>.</P></DD>
<DT ID="SCREEN">Screen origin</DT>
<DD><P>The first ReGIS coordinate at the upper-left corner of the screen. This coordinate
is [0,0].</P></DD>
<DT ID="SHADING">Shading reference line</DT>
<DD><P>A horizontal or vertical line that ReGIS uses when shading images. Shading
occurs between the shading reference line and the point being drawn or moved
to.</P></DD>
<DT ID="UNBOUNDED">Unbounded position stack</DT>
<DD><P>An option to the ReGIS vector or position command that lets you save a nonexistent
position by pushing it onto a stack. The active position does not move
when the saved dummy position is popped off the stack. See <A HREF="#BOUNDED">bounded position
stack</A>.</P></DD>
<DT ID="UNIT">Unit cell</DT>
<DD><P>The maximum size of each display character within the <A HREF="#DISPLAY">display cell</A>.</P></DD>
<DT ID="VECTOR">Vector</DT>
<DD><P>A directed line. You use the ReGIS vector command to draw lines.</P></DD>
<DT ID="VERTEX">Vertex</DT>
<DD><P>One of the points defining a polygon.</P></DD>
</DL>
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